
import java.lang.reflect.*;

public class OSXAdapter implements InvocationHandler {

	protected Object targetObject;
	protected Method targetMethod;
	protected String proxySignature;

	static Object macOSXApplication;

	// Pass this method an Object and Method equipped to perform application
	// shutdown logic
	// The method passed should return a boolean stating whether or not the quit
	// should occur
	public static void setQuitHandler(Object target, Method quitHandler) {
		setHandler(new OSXAdapter("handleQuit", target, quitHandler));
	}

	// Pass this method an Object and Method equipped to display application
	// info
	// They will be called when the About menu item is selected from the
	// application menu
	public static void setAboutHandler(Object target, Method aboutHandler) {
		boolean enableAboutMenu = (target != null && aboutHandler != null);
		if (enableAboutMenu) {
			setHandler(new OSXAdapter("handleAbout", target, aboutHandler));
		}
		// If we're setting a handler, enable the About menu item by calling
		// com.apple.eawt.Application reflectively
		try {
			Method enableAboutMethod = macOSXApplication.getClass()
					.getDeclaredMethod("setEnabledAboutMenu",
							new Class[] { boolean.class });
			enableAboutMethod.invoke(macOSXApplication,
					new Object[] { Boolean.valueOf(enableAboutMenu) });
		} catch (Exception ex) {
			System.err.println("OSXAdapter could not access the About Menu");
			ex.printStackTrace();
		}
	}

	// Pass this method an Object and a Method equipped to display application
	// options
	// They will be called when the Preferences menu item is selected from the
	// application menu
	public static void setPreferencesHandler(Object target, Method prefsHandler) {
		boolean enablePrefsMenu = (target != null && prefsHandler != null);
		if (enablePrefsMenu) {
			setHandler(new OSXAdapter("handlePreferences", target, prefsHandler));
		}
		// If we're setting a handler, enable the Preferences menu item by
		// calling
		// com.apple.eawt.Application reflectively
		try {
			Method enablePrefsMethod = macOSXApplication.getClass()
					.getDeclaredMethod("setEnabledPreferencesMenu",
							new Class[] { boolean.class });
			enablePrefsMethod.invoke(macOSXApplication,
					new Object[] { Boolean.valueOf(enablePrefsMenu) });
		} catch (Exception ex) {
			System.err.println("OSXAdapter could not access the About Menu");
			ex.printStackTrace();
		}
	}

	// Pass this method an Object and a Method equipped to handle document
	// events from the Finder
	// Documents are registered with the Finder via the CFBundleDocumentTypes
	// dictionary in the
	// application bundle's Info.plist
	public static void setFileHandler(Object target, Method fileHandler) {
		setHandler(new OSXAdapter("handleOpenFile", target, fileHandler) {
			// Override OSXAdapter.callTarget to send information on the
			// file to be opened
			public boolean callTarget(Object appleEvent) {
				if (appleEvent != null) {
					try {
						Method getFilenameMethod = appleEvent.getClass()
								.getDeclaredMethod("getFilename",
										(Class[]) null);
						String filename = (String) getFilenameMethod.invoke(
								appleEvent, (Object[]) null);
						this.targetMethod.invoke(this.targetObject,
								new Object[] { filename });
					} catch (Exception ex) {

					}
				}
				return true;
			}
		});
	}

	// setHandler creates a Proxy object from the passed OSXAdapter and adds it
	// as an ApplicationListener
	public static void setHandler(OSXAdapter adapter) {
		try {
			Class applicationClass = Class
					.forName("com.apple.eawt.Application");
			if (macOSXApplication == null) {
				macOSXApplication = applicationClass.getConstructor(
						(Class[]) null).newInstance((Object[]) null);
			}
			Class applicationListenerClass = Class
					.forName("com.apple.eawt.ApplicationListener");
			Method addListenerMethod = applicationClass.getDeclaredMethod(
					"addApplicationListener",
					new Class[] { applicationListenerClass });
			// Create a proxy object around this handler that can be
			// reflectively added as an Apple ApplicationListener
			Object osxAdapterProxy = Proxy.newProxyInstance(
					OSXAdapter.class.getClassLoader(),
					new Class[] { applicationListenerClass }, adapter);
			addListenerMethod.invoke(macOSXApplication,
					new Object[] { osxAdapterProxy });
		} catch (ClassNotFoundException cnfe) {
			System.err
					.println("This version of Mac OS X does not support the Apple EAWT.  ApplicationEvent handling has been disabled ("
							+ cnfe + ")");
		} catch (Exception ex) { // Likely a NoSuchMethodException or an
									// IllegalAccessException loading/invoking
									// eawt.Application methods
			System.err.println("Mac OS X Adapter could not talk to EAWT:");
			ex.printStackTrace();
		}
	}

	// Each OSXAdapter has the name of the EAWT method it intends to listen for
	// (handleAbout, for example),
	// the Object that will ultimately perform the task, and the Method to be
	// called on that Object
	protected OSXAdapter(String proxySignature, Object target, Method handler) {
		this.proxySignature = proxySignature;
		this.targetObject = target;
		this.targetMethod = handler;
	}

	// Override this method to perform any operations on the event
	// that comes with the various callbacks
	// See setFileHandler above for an example
	public boolean callTarget(Object appleEvent)
			throws InvocationTargetException, IllegalAccessException {
		Object result = targetMethod.invoke(targetObject, (Object[]) null);
		if (result == null) {
			return true;
		}
		return Boolean.valueOf(result.toString()).booleanValue();
	}

	// InvocationHandler implementation
	// This is the entry point for our proxy object; it is called every time an
	// ApplicationListener method is invoked
	public Object invoke(Object proxy, Method method, Object[] args)
			throws Throwable {
		if (isCorrectMethod(method, args)) {
			boolean handled = callTarget(args[0]);
			setApplicationEventHandled(args[0], handled);
		}
		// All of the ApplicationListener methods are void; return null
		// regardless of what happens
		return null;
	}

	// Compare the method that was called to the intended method when the
	// OSXAdapter instance was created
	// (e.g. handleAbout, handleQuit, handleOpenFile, etc.)
	protected boolean isCorrectMethod(Method method, Object[] args) {
		return (targetMethod != null && proxySignature.equals(method.getName()) && args.length == 1);
	}

	// It is important to mark the ApplicationEvent as handled and cancel the
	// default behavior
	// This method checks for a boolean result from the proxy method and sets
	// the event accordingly
	protected void setApplicationEventHandled(Object event, boolean handled) {
		if (event != null) {
			try {
				Method setHandledMethod = event.getClass().getDeclaredMethod(
						"setHandled", new Class[] { boolean.class });
				// If the target method returns a boolean, use that as a hint
				setHandledMethod.invoke(event,
						new Object[] { Boolean.valueOf(handled) });
			} catch (Exception ex) {
				System.err.println("OSXAdapter was unable to handle an ApplicationEvent: "+ event);
				ex.printStackTrace();
			}
		}
	}
}